Bulletin of the American Physical Society
2018 Joint Fall Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 63, Number 18
Friday–Saturday, October 19–20, 2018; University of Houston, Houston, Texas
Session G01: Poster Session |
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Chair: Donna Stokes, University of Houston Room: TDECU Football Stadium Club Suite |
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G01.00001: Comparative Study of Electromagnetic Effects on Bacterial Growth Joel A Johnson, Samina Masood A comparative study of the growth rate and physical changes for Escherichia coli bacteria is conducted under different types of magnetic fields. Both liquid nutrient broth and solid agar were used at room temperature to compare the effect of media as well. We found significant changes in the growth rates under different kind of magnetic fields. Liquid and solid media were effected differently as well. |
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G01.00002: Mathematical Model Developments for Thermochemical Ablation Samuel S Oedi Thermochemical ablation (TCA) is a novel approach to minimally invasive therapy of Hepatocellular carcinoma (HCC). In TCA, targeted tissue is treated with the heat released and the salt formed from an acid-base injection. The by-products create an environment that may increase the diameter of the lethal zone, and serve as a local diffusion reservoir to reduce the risk of local recurrence. In this poster, the impact of heat and salt on treated cells is studied by developing a mathematical model to evaluate TCA injections. The most apparent changes induced by temperature and concentration in TCA are the changes in the ablative solutions and in the targeted tissue. We show that Laliberté and Cooper's model is useful for describing the changes in density of the ablative solutions at temperatures and concentrations that are relevant to TCA. We also show that the modified Arrhenius model can accurately estimate tissue damage on different HCC cells. Finally, we develop a procedure to manufacture foam phantoms that mimic liver porosity. A fully developed liver-mimicking phantom will provide a reproducible, controlled environment to validate all of the models' predictions. |
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G01.00003: Using Python to Create Light Curves of White Dwarf Stars Roel Rolando Olvera, Joshua T Fuchs The light curves of variable white dwarfs can be used to measure pulsational properties of single white dwarfs and geometric properties of white dwarfs in binaries. These properties can assist our understanding of the structure and evolution of various white dwarfs. We will introduce a new program to analyze photometry collected with the SOAR Telescope. This program is written entirely in Python. We will present initial results looking at two pulsating white dwarfs and discuss ways to improve our program. |
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G01.00004: Mathematical Methods of Imaging Mostofa Ahmed Hisham Imaging techniques have a wide array of applications in various fields of technology. One such application is medical imaging, such as the use of Computerized Assisted Tomography (CAT) or Magnetic Resonance Imaging (MRI). The mathematical techniques behind such imaging technologies will be discussed. In particular, the data measured by the CAT scanners correspond to the Radon transform of the image function, which one would like to recover. However, the Radon transform presents the data in a sinusoidal form, which must then be modified into the image of the object by the Fourier transform, certain filtering, and the inverse Fourier transform. The back-projection will be applied on this modified set of data. This final data set should reflect the original object provided by the original measurements. The Radon transforms of several elementary shapes will be presented. Some variations on the Radon Transform will also be discussed, such as the effect of having limited data from the Radon Transform on the final reconstructed image. |
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G01.00005: Using material elasticity and electron density in multi-modality imaging Galen Q Lytle, Nathaniel R Fredette, Mini Das Ultrasound imaging is a common modality in clinical settings, used for its non-destructive, low-cost, and non-invasive properties. However, it has limited resolution for deep imaging. X-ray imaging is used to achieve these high-resolution images at great depth throughout the body but must be used sparingly so as to avoid ionizing biological tissue. Using low-dose x-ray imaging to determine properties of the target, especially in creating preliminary mass density maps, improves the diagnostic potential of ultrasound imaging. Recent advances in spectra X-ray imaging have allowed accurate electron density maps of objects to be yielded. This tomographic electron density information can be explored in conjunction with 3D ultrasound techniques which yields a map of the object’s elasticity. Mass density maps can also deliver verifying information about the compressibility of different objects by deriving Young’s modulus. We will test these ideas via preliminary studies using tissue-mimicking phantoms. |
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G01.00006: Using Linked Scatter Plots to Determine the Presence of Rare Stellar Remnants Andrew H Hamilton There are only eight confirmed Low Accretion Rate Polars (LARP) known at the time. Finding and characterizing more of these rare stellar remnants will help us determine their evolution. We have developed a program that uses Linked Scatter Plots to make candidate lists of stars that exhibit properties similar to these known LARPs. We use SDSS, WISE, GALEX, and X-MM Newton observations of the confirmed LARPs to automatically create a set of filter conditions to sort through large surveys and identify candidate LARPS. We will discuss our determination of useful filters, present our initial candidate list, and discuss follow-up work. |
(Author Not Attending)
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G01.00007: Equation of State of Neutron Stars Josilyn Valencia I review the so-called equation of state (EoS) of neutron stars derived from microscopic nucleon-nucleon forces. In particular we test new models involving the cluster contributions to the EoS and compare them to the predictions based on the Tolman-Oppenheimer-Volkoff structural equation. |
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G01.00008: Computation of vacuum polarization tensor in QED plasma under varied conditions Samina Masood, Faiz Khan We study the vacuum polarization tensor at the component level in a hot and dense medium to understand the propagation of light in a medium. For this purpose we compute each and every component of the vacuum polarization tensor as a function of temperature and chemical potential. We include the statistical corrections to the QED coupling and the electron charge to study this effect. We compute the components of vacuum polarization tensor for different ranges of temperature and chemical potential. |
(Author Not Attending)
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G01.00009: Abstract Withdrawn
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G01.00010: First principles study on the piezoelectricity of KNN alloys Yuting Peng, Zhi Tan, Jiao An, Qiming Zhang To understand the physical significance for the high piezoelectric response in K1-xNaxNbO3 (KNN) material, the geometric structure, total energy, elastic constant, Born effective charge and piezoelectric constant of orthorhombic K1-xNaxNbO3 perovskite solid solutions at various x (from 0 to 1) are investigated using first principles calculations for supercells. The results show that lattice parameters of K1-xNaxNbO3 supercells decrease monotonously with the increasing value of x. However, the piezoelectricity exhibits parabolic-like relation with x, and the longitudinal piezoelectric coefficient d33* reaches a maximum at about x=0.5625, where the morphotropic phase boundary is expected to occur in K1-xNaxNbO3 material. |
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G01.00011: Responses of Multiwalled Carbon Nanotubes of Different Diameters to Microwave Irradiation Parker Adamson, Scott Charles Williams We studied the ultraviolet, visible, and infrared radiation emitted by multiwalled carbon nanotubes of different diameters when exposed to 2.45 GHz microwaves. A comparison of the spectra suggests that multiwalled carbon nanotubes with larger diameters emit radiation of greater intensity than those with smaller diameters. Furthermore, the multiwalled carbon nanotubes continued to emit radiation over the course of several microwave-irradiation cycles, with no degradation in the intensity of the emitted radiation. A comparison of Raman D- to G-band peak-intensity ratios revealed that microwave-irradiation did not significantly impact the multiwalled carbon nanotubes’ defect densities. The results of our experiments suggest that multiwalled carbon nanotubes may have the potential for use in lighting technologies, and that ohmic heating caused by the polarization of the multiwalled carbon nanotubes in the microwave field is likely responsible for the observed emissions of visible and infrared radiation. |
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G01.00012: Creating a Wave-Powered Robot Audrey Colegrove, Jacob Jimerson In 2008 a 9.5-meter catamaran, the Suntory Mermaid II, traveled from Honolulu, Hawaii to Wakayama, Japan using two fins that converted wave energy into forward motion. Despite the success of this Wave Devouring Propulsion System, little has been published about how it works. This is somewhat surprising since a wave-powered boat design would be ideal for a sensor platform that could travel over a wide area for an extended period without refueling. The goal of this project was to create a working model based on this method, and to analyze its performance. We will present our results to date and plans for future improvement. |
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G01.00013: Developing an Underwater Game Camera Ty Stubbs, Luke Hicks The goal of this project was to create an underwater game camera that could track and observe fish and other aquatic creatures in their natural habitat. Such a device would be able to monitor the behavior of wildlife over a period of several days without them being disturbed by the presence of divers. A variety of electronic components are need to create a reliable game camera and we have investigated a number of possible choices. Our final design is rugged, inexpensive and can take several high quality pictures a minute. Our poster will describe the details of this design and our plans to deploy this game camera. |
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G01.00014: Low temperature magneto-transport properties of encapsulated WTe2 flakes Xurui Zhang, Xiaoyan Shi We report low temperature electronic transport measurements of encapsulated semimetallic WTe2 flakes with different thickness. Magnetoresistance and Hall measurements reveal two-carrier behavior in all samples, which is consistent with band structure calculations. However, thicker sample shows a much larger charge imbalance between electron and hole concentrations than thinner one where the electron and hole are almost balanced down to 20 mK. Furthermore, angle dependence of Rxx reveals strong anisotropy in samples with different thickness. |
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G01.00015: Properties of carrier traps in diode and RRAM devices via DLTS Clint Austin Boldt, Md. Abdul Ahad Taludker, James Nick Talbert, Luisa Scolfaro, Wilhelmus Johannes Geerts Defects and impurities are electrically active deformities in periodic lattice and change the properties of the materials. Active defects work as a charge carrier traps and occupy energy levels in the energy band gap, consequently change the electrical properties of the material. Deep Level Transient Spectroscopy (DLTS) is a powerful technology for the detection and identification of electrically active defects (known as traps) in semiconductors. It is a method to determine the energy levels via time dependent capacitance measurement in the bandgap and capturing cross sections of deep level traps in a semiconductor. In DLTS a bias voltage is applied to fill the traps with charge carriers and returned to normal bias, the traps will empty over time and changes the device’s capacitance. The behavior of transient capacitance over a range of different temperatures reveals traps position and properties. An IN4007 commercial diode was used to calibrate the system with the temperature and appropriate fill pulse settings. The measurement was analyzed using rate windows analysis or transient fits. DLTS and IVT measurements on the IN4007 and Si/NiFeOxide/Au devices will be discussed. |
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G01.00016: Crystal Structures and the Electronic Properties of Silicon-Rich Silicon Carbide by First Principle Calculations Noura Dawas Alkhaldi, Sajib K Barman, Muhammad Nurul Huda Silicon carbide has been used in a variety of applications such as solar cells material due to its high stability. Obtaining Silicon-rich silicon carbide materials are necessary to tune the band gap for efficient solar light absorptions. In addition, thermodynamically stable Si-rich SiC materials can be used in solar cell applications without requiring a pure grade silicon or pure grade silicon carbide materials which are very expensive materials. We have used density functional theory (DFT) calculations to examine different structures of silicon-rich silicon carbide to predict stable structures. Different configurations of silicon and carbon atoms in silicon-rich silicon carbide structures have been considered because the configurations play a significant role in getting stable results. The electronic structures have been studied, and the total energies have been calculated as well as the formation energies. These results will be presented. The results show that hexagonal-phases are more favorable structures than other silicon-rich silicon carbide structures due to their more covalent nature of bonding compared to the cubic counterpart. |
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G01.00017: Iron Gallium Magnetostriction Measurement Setup Noel Gamez, Wilhelmus Johannes Geerts, Luisa Scolfaro, William Spencer, Giri Joshi Due to the high drive towards improved efficiencies in vibration sensors, there is a search for materials with high magnetostriction. Magnetostriction is the magnetoelastic coupling in response to a rotation of the magnetic moments. An external rotating field will cause the material to deflect at a value proportional to the magnetostriction constant. We built a setup that produces a rotating field to induce uniaxial in-plane stress through two sets of Helmholtz coils while a photonic sensor measures the sample’s deflection. Fe80Ga20samples were prepared by DC magnetron sputtering on Si wafers (250W deposition power, 1.7mTorr, 9.75sccm, Ar flow, 170 nm film thickness). Samples were sputtered at RT and 300 Celsius. The crystal structure of the thin films was checked with a Rigaku diffractometer. The hysteresis curves of the FeGa samples were measured with a MicroSense Vibrating Sample Magnetometer. The RT sample had a moment density of 1257.56emu/cm3and a coercivity of 17-35 Oe. The sample deposited at 300C had a magnetic density of 866.83emu/cm3and a coercivity of 25 Oe. The result of the magnetostriction measurements on these samples will be discussed. |
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G01.00018: Projectile survival during H- and H collisions with Cu surfaces Bogdana Mioara Bahrim, Jamie Michelle Stafford, Boris Makarenko Survival probabilities for H- and H projectiles scattered from Cu(111) and Cu(100) surfaces are reported for energies ranging from 0.5 keV to 5 keV, and exit angles ranging from 20o to 90o. The projectile energy, exit angle, distance of closest approach to surface, and especially the metal band structure are important factors that influence the survival. Also, scattering on different faces of Cu yields different results, thus revealing a strong crystal effect on the ion/neutral fractions. At low perpendicular energies, the H- survival on Cu(100) is smaller than on Cu(111), and continues to decrease as the energy decreases. For higher energies, the H- survival on Cu(100) becomes higher than on Cu(111). For very fast collisions, the incoming projectile does not feel the band structure anymore, the copper surface behaves like a jellium, and the survival on both Cu(100) and Cu(111) is the same. The H survival on Cu(100) seems to be energy independent. On the contrary, the H survival on Cu(111) is both energy and angle dependent, and it is smaller. The study of PDOS shows that strong atom-surface interactions at short distances and the role played by the surface state are important factors in determining the neutral fractions after scattering. |
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G01.00019: Diamond Magnetic Microscopy of Individual Superparamagnetic Nanoparticles Nathan Arnold, Victor Marcel Acosta, Abdelghani Laraoui, Ilja Fescenko, Janis Smits Nitrogen-Vacancy (NV) centers in diamonds are currently being used as a quantum sensor for imaging magnetic fields at the nanometer scale due to their magnetic field dependent fluorescence. We have applied this method to characterize Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) for biomedical applications. Isolated 22 nm SPIONs were dispersed on a diamond substrate with a 200 nm thick NV layer, and images of SPION stray magnetic fields were obtained by optically detected magnetic resonance imaging. When subjected to a bias magnetic field the SPIONs form their own magnetic dipole, which was imaged and analyzed with a Mathematica code that fit the magnetic dipole equation to the image. Magnetic images for dozens of individual SPIONs were obtained as a function of applied field and as a function of time after abruptly turning off an applied field. From this analysis we seek a more fundamental understanding of how minor differences in size and shape of SPIONs can have drastic changes to their superparamagnetic behaviors. |
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G01.00020: Quantum Dynamics of a Qubit Coupled to a Harmonic Oscillator Ray M Hagimoto, Jean-Francois S Van Huele We investigate the quantum dynamics of the forced harmonic oscillator |
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G01.00021: Gas Sensing in a Microresonator System Using Non-Adiabatic Tapered Fibers Lucas Alexander Blake, Sreekul Raj Rajagopal, Albert T Rosenberger Adiabatically tapered fibers have commonly been used to excite whispering gallery modes (WGMs). It has recently been shown that non-adiabatically tapered fibers can enhance refractive index sensing. The light within a non-adiabatic taper transition excites both fundamental and higher-order fiber modes, whereas an adiabatic taper transition only excites the fundamental fiber mode. The sensing enhancement comes from the interference between different fiber modes. We have theoretically shown that enhancement is also possible for absorption sensing. The enhancement can be predicted by the measured power when the modes are in and out of phase. The enhancement is proven by sending light through the adiabatic side of an asymmetrically tapered fiber. We have shown this enhancement using a setup combining the asymmetric tapered fiber and a hollow bottle resonator (HBR) with internal analyte. The light absorbed by the analyte results in changes in the dip depth of the WGM. The ratio of changes, non-adiabatic to adiabatic, shows the enhancement factor. For carbon dioxide an enhancement factor of 150 was found, in agreement with the theoretical model. |
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G01.00022: Radiation-hardness Studies with Cerium-doped Fused-silica Fibers Esra Kendir, Nural Akchurin, Jordan Damgov, Federico De Gui, Shuichi Kunori, Serafettin Yaltkaya We continue our R&D effort in developing scintillating and wavelength shifting fibers by doping fused-silica fibers with cerium. In this report, we summarize fibers’ radiation-hardness by providing experimental data and a predictive model based on second-order rate equations. Five different types of cerium-doped and a clear fused-silica fibers were exposed to the gamma radiation (60Co) at different dose rates up to 100 kGy. We evaluated radiation-induced transmission losses as well as photoluminescence efficiency in a wide wavelength range (400-1000 nm). We also present measurements of the effective numerical aperture upon exposure to radiation and offer some thoughts on the use of these fibers in particle physics as well as in other wide-ranging applications. |
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G01.00023: Scanning Diffracted-Light images Hawra Alghasham A 4-f imaging arrangement of lenses with a camera, and a rotating slit placed at the Fourier plane of the system, was used to obtain the optical disturbance produced by a macroscopic sample. The sample was illuminated by collimated beams from white-light and thermal radiation sources. The agreement between simulated and experimental results, obtained by processing the captured images using a Fourier ptychographic algorithm, demonstrates that scanning with the slit, the direction of the light that is diffracted by the sample, permits achieving the image diversity necessary for the successful implementation of the scanning diffracted-light imaging technique.
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G01.00024: Subwavelength resolution using scanning diffracted-light microscopy and plasmonic ultra-thin condensers Sueli Skinner Ramos, Hira Farooq, Hawra Alghasham, Ayrton A. Bernussi, Luis Grave de Peralta Fourier Ptychographic Microscopy techniques are phase-recovery imaging algorithms capable of producing high-resolution images of objects smaller than Rayleigh resolution limit. Traditionally, these algorithms require long exposure times, multiple iterations, and suffer from low image diversity. We developed a new technique called Illumination Direction Multiplexing-Scanning Diffracted-Light Microscopy (IDM-SDLM) that uses a plasmonic Ultra-thin condenser (UTC), and a rotating slit placed at the back focal plane to overcome these issues. We demonstrated enhanced imaging capabilities of plasmonic crystals with periods (p) in the range λ/(NAo + NAc) < p < λ/(2NAo), using plasmonic UTCs with NAc > NAo, which set the precedent for a novel kind of optical nanoscope. |
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G01.00025: Machine Learning Model to Predict Failure Modes of TRISO Particles under High-Temperature Gas-Cooled Reactor Accident Conditions Marielle D Gaspar, Seth Pritchard, Amanda D Fernandez, Elizabeth S Wood Tristructured istropic particles, which contain a central kernel of uranium oxycarbide and are surrounded by a multilayered ceramic shell, are the fuel form proposed for high temperature gas-cooled reactors (HTGRs) and very high temperature gas-cooled reactors (VHTRs). These next generation nuclear reactors are proposed for operation at temperatures in excess of 600°C. Though He is the primary fuel coolant, the fuel form could see appreciable amounts of moisture, oxygen, carbon monoxide and carbon dioxide during certain accident scenarios. The exposure to a highly corrosive, mixed gas atmosphere can impact the integrity of the fuel form. The research presented incorporates machine learning approaches using the established thermodynamics of SiC-oxidant reactions and experimental data acquired to enable the prediction of catastrophic reactions, failure atmospheres, and SiC reactions with gas mixtures relevant to certain HTGR and VHTR accident scenarios. |
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G01.00026: Enhanced Visible Light Activity in Titania Nanotube Based Heterojunction Photocatalysts for Solar Fuel Generation Ram Neupane, Maggie Paulose, Oomman Varghese The world energy consumption has been steadily increasing with technological advancements and growing population. Bulk of this energy is currently derived from fossil fuels, which are known to be responsible for the greenhouse gas emission and associated environmental problems. Solar fuels such as hydrogen derived from water using semiconductor photocatalysts is a sustainable approach. Nonetheless, most photocatalysts hold drawbacks such as wide band gap and high recombination rate of photo-generated electrons and holes, limiting the practical applications. In a recent study, it was demonstrated that a visible light active photoelectrode for photoelectrochemical water splitting could be developed by coupling the wide band gap titanium dioxide nanotubes with two dimensional (2D) narrow band gap iron oxide called hematene (Nat. Nanotech., 13, 602-609, 2018). We have extended the studies to a 1D titania/2D FeTiO3 heterostructure and observed photo-generated carrier transfer from 2D FeTiO3 to 1D TiO2 through the heterojunction even though the positions of the conduction bands were not favorable for such a transfer. In this presentation, we will discuss these results and the enhanced visible light driven solar photoelectrochemical hydrogen generation using these photoelectrodes.
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G01.00027: Relaxivities of Lanthanide-based MRI Contrast Agents at Low Magnetic Field David Williams Clark, Christopher Parish, Lloyd Lumata Lanthanide complexes such as Gd-DOTA are widely-used as contrast agents in magnetic resonance imaging (MRI) due to their excellent relaxation properties and chemical stability in vivo. Such MRI contrast agents are optimized at the normal clinical MRI field strengths of 3 T or higher. The recent availability of preclinical MRI scanners operating at low magnetic fields such as 1 T or at earth’s magnetic field requires that these lanthanide-based MRI contrast agents to be optimized at these conditions. In this work, we have characterized the relativities of aqueous solutions of lanthanide complexes at fields of 1 T and at earth’s magnetic field (~0.3 Gauss). In particular, we have measured the concentration dependence of both the proton spin-lattice (T1) and spin-spin (T2) relaxation times of Gd-DOTA and Ho-DOTA solutions. The spin physics and potential applications of these results will be discussed. This study is supported by Welch grant AT-1877, DOD grant W18XWH-17-0303, and CPRIT grant RP180716. |
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G01.00028: Variability of the Balmer Emission Lines in T Tauri Stars Hilary C. Utaegbulam, Christopher M. Johns-Krull Classical T Tauri stars (CTTSs) are young, roughly solar mass, pre |
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G01.00029: Structural, Electronic, Magnetic, and Electrochemical Properties of LiTi2(PO4)3-coated LiNi1/3Co1/3Mn1/3O2 Cathode Material Richard Baham, Brandon Sands, Clayton Ellinwood, Gan Liang, Lu-Lu Zhang, Ji-Qing Wang, Xue-Lin Yang The structural, electronic, magnetic, and electrochemical properties of LiTi2(PO4)3-coated LiNi1/3Co1/3Mn1/3O2 cathode material are studied by x-ray diffraction, scanning electron microscopy, x-ray photoemission, magnetic susceptibility, electrochemical impedance spectroscopy, and charge/discharge profile measurements. Our results reveal that both the pristine and the LiTi2(PO4)3-coated LiNi1/3Co1/3Mn1/3O2 samples have the same crystal structure and lower cation mixing. The valence values of the elements Ni, Mn, Co, and Ti in the samples are found to be +2, +3, +4, and +4, respectively. Compared with the pristine electrode, the LiTi2(PO4)3-coated electrode exhibits higher capability and better cycling stability. The LiTi2(PO4)3-coated LiNi1/3Co1/3Mn1/3O2 electrode delivers a high initial capacity of 191.5 mAh g-1 with a desirable capacity retention ratio of 84.5 % after 100 cycles at 0.5 C. The superior capability and cycling stability of the LiTi2(PO4)3-coated LiNi1/3Co1/3Mn1/3O2 electrode may be attributed to the reduced charge transfer resistance, enhanced electronic conductivity, increased lithium ion diffusion coefficient, and the protecting effect due to LiTi2(PO4)3 coating. |
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G01.00030: Intensity Modulated Photovoltage and Photocurrent Spectroscopy Studies on Perovskite Solar Cells Anthony Martinez, Alexander Halsey, Maggie Paulose, Dhan Rana, Oomman K Varghese Organometallic perovskite solar cells (PSCs) are a novice device that has got much attention due to the achievement of power conversion efficiency of about 22% shortly after its inception. The light absorbers primarily used in perovskite solar cells, methylammonium lead halides (CH3NH3PbX3, where X is a halogen), have a structure like Calcium Titanium Oxide (CaTiO3). A problem associated with these organometallic materials is their interaction with the environment causing stability problems to the devices. A critical understanding of the environmental impact on the structure and kinetic properties would help to improve the stability of the devices. We recently developed a setup for intensity modulated photovoltage/photocurrent spectroscopies (IMVS and IMPS respectively) to study the carrier transport properties in these solar cells. Instead of a frequency response analyzer often used in this technique, we employed a lock-in amplifier to modulate the intensity of a light source and measure the current/voltage response of the devices. In this presentation, we will discuss the instrumentation and the results of the carrier transport property studies performed on the orthorhombic, tetragonal and cubic phases of CH3NH3PbI3 upon their exposure to different humidity conditions. |
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G01.00031: First Principle Polaron Modeling in Hybrid Perovskites Using the GGA+U Method Eric Welch, Amanda Neukirch, Sergei Tretiak, Petr Obraztsov, Dmitry Lyashenko, Pavel Chizhov, Kuniaki Konishi, Natsuki Nemoto, Makoto Kuwata-Gonokami, Alexander Obraztsov, Alex Zakhidov Lead halide hybrid perovskites (HPs) are the benchmark, state-of-the-art materials in third generation perovskite solar cells, achieving a power conversion efficiency of over 22%. Yet, the underlying photo-physical properties of HPs are still under debate. Here we use density functional theory within the generalized gradient approximation with a Hubbard correction (GGA+U) to study structural properties, band structures, and charge carrier dynamics in HPs. Our preliminary DFT+U simulations reveal the formation of hole polarons in HPs with different halides, which have profound implications on device operation and stability. Moreover, we argue that polaron induced loss of inversion symmetry and enhanced Rashba splitting might be responsible for our recent experimentally observed room-temperature ultrafast photocurrent and free-space terahertz emission generation from unbiased CH3NH3PbI3 HPs. Polarization dependence of the observed photoresponse is consistent with the Bulk Photovoltaic Effect, which may enable next generation perovskite solar cells with efficiency above the Shockley–Queisser limit. |
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G01.00032: An intrinsic origin of enhanced piezoelectricity in KNN lead-free ceramics studied by first-principles calculations Zhi Tan, Yuting Peng, Jiao An, Qiming Zhang The intrinsic piezoelectricity in orthorhombic KN and KNN alloys has been investigated using first-principles methods. We found that the longitudinal piezoelectric coefficient of orthorhombic KN and KNN piezoceramics was mainly contributed by the d33 and d15 of their single crystal. The calculated longitudinal piezoelectric coefficients are 52.7 pC/N and 89.3 pC/N in KN and KNN ceramics, respectively, which confirms the enhanced piezoelectricity in KNN piezoceramics. The enhanced piezoelectricity mainly comes from the increased response of internal coordinates of Na and O atoms to a macroscopic strain. The underlying mechanism is that the smaller atomic size of Na gives a larger free space for itself and adjacent O atoms in the perovskite structure, increasing the local structural instability. Our result provides a microscopic insight to understand the enhanced piezoelectricity in KNN piezoceramics. |
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G01.00033: Temperature Dependence of the Magnetic Properties of Reactive RF Sputtered NiFeO Thin Films Selena R Najar, Joselyn Lesikar NiFeO is an antiferromagnetic material, usable in hard-disk reading heads and spintronic devices. Its properties of interest in this research are the magnetic permeability and the temperature dependence of its magnetization. Reactive RF co-sputtering was used to deposit Ni0.81Fe0.19O2-δ films. Films were deposited on p-type Si at different oxygen flow rates (0.7 and 1.0 sccm O2flow). The experiment was designed to test how the oxygen flow used during deposition affects the magnetic properties of the films. Both NiO and FeO are antiferromagnetic with Neel temperatures of respectively 525 and 198 Kelvin. It is expected that Fe doping of NiO will allow to fine-tune the Neel temperature. In addition, RF-sputtered NiFe oxide samples sputtered at low oxygen flow have a residual magnetic moment caused by oxygen vacancy clusters. Hysteresis loops and MT curves were measured with a MicroSense VSM in fields up to 2.2 tesla between 94K and 973K. The magnetic moment of the samples decreases with temperature and becomes zero below 620K (0.7 sccm) and 740K (1.0 sccm). An irreversible change of the samples was observed after temperature exposure above 773K. |
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G01.00034: Exploring the Effect of Environmental Factors on Radon Plate-out Taylor Nicole Wallace Radon is an inert, radioactive gas that occurs naturally and disperses quickly. As it decays, the resulting daughters can “plate out” (stick) on surfaces, which can contaminate important components in dark matter experiments. Subsequent decays can create backgrounds that mimic signals, so it is imperative to minimize the amount of radon that plates out. To conduct studies on radon plate-out, a Pylon RN-1025 flow-through source was used to create a calibrated radon environment. These studies showed a rational relationship between airflow through the source and radon concentration in the exposure chamber. A flow of 4 SCFH through the source was found to be the optimal flow to use for plate-out tests as it provided a high equilibrium concentration of 1270-1390 Bq/m3 while still overpressuring the system. Initial tests have shown an activity of roughly 0.044±0.002 Bq after correcting for detector efficiency. However, additional trials and calculations are needed for confirmation. Future tests will be performed to determine the effect of wind speeds on the radon plate-out efficiency. |
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G01.00035: Studies on High Granularity Calorimeter Upgrade to the Compact Muon Solenoid Experiment at CERN Samuel R Cano, Jake Noltensmeyer The goal of my research is to optimize the design of High Granularity Calorimeter (HGCAL) for Jet and MET measurements in preparation for the High Luminosity upgrade to the Compact Muon Solenoid (CMS) Experiment during Long Shutdown 3, beginning in 2024. This upgrade is crucial to overcome hardware radiation tolerance issues and to produce better structure analysis and particle identification. To do so we performed several studies involved software to simulate particle collisions with different HGCAL detector geometries and analyzed the resulting histograms. The studies revealed bugs in detector geometry configuration and tested the efficiency of the simulations to produce accurate particle collision results. These studies are a continuation of software development to effectively construct the most useful detector design for the next CMS upgrade. |
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G01.00036: Parallel to Serial Powering Calvin Ainsworth, Evan Van de Wall The Large Hadron Collider (LHC) is going from parallel to serial powering, and Oklahoma State University's high energy department was tasked with designing the power supply for the switch. I was tasked to run test on FEI4B front end chips, and these chips are the same chips that are used as the pixel detectors within the LHC. However, with the chips that I was working with did not have pixel detectors on them, because I was only worried about the noise levels of the electronics. The electronics were important, because I would be comparing the data from a commercial power supply to the power supply that Oklahoma State produced. Before gathering data to compare the two power supplies, the data for parallel and serial powering from a commercial power supply was needed, and when the data collection for this was done then the data for Oklahoma State's power supply could begin. |
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G01.00037: Anode Development for NEXT at UT-Arlington HEP Fahad S Karim Searches for neutrinoless double beta decay are contingent upon the proper and indisputable detection of what may be a very small number of signal events, over a large background of gamma rays. One method of collecting the scintillation light from such events is through use of a Silicon Photomultiplier (SiPM) wheel. This device must be optically transparent (to allow for the light to pass through the wheel unobstructed and for the wheel) and electrically conductive (to function as a TPC anode). Prominent candidates for the substrate material are Static-Dissipative Acrylic and standard acrylic coated with a highly-conductive ink named PEDOT. On the other hand, SiPMs are intrinsically non-responsive to wavelengths within the xenon scintillation spectrum. Tetraphenyl butadiene (TPB), an organic wavelength shifter, has been proposed as coating to shift these wavelengths to the sensitive range of the optical detectors. The effects of TPB on incoming light have been studied, including attenuation lengths, node behavior (behavior at the TPB-acrylic interface) and other such factors. I will present these studies, which have helped fine-tune the model for an ideal anode for the NEXT experiment. |
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G01.00038: Simultaneous Photometry: Vetting Exoplanets via the Transit Method Ethan McGee The transit method of detecting exoplanets involves measuring the decrease in the amount of light coming from a star when the planet passes in front of its host star. Space-based missions such as Kepler record these light curves and catalog new exoplanet candidates. However, these candidates may often be false-positives, such as eclipsing binary (EB) stars. Since EB stars are often composed of different spectral types, the measured transit depth can vary in different regions of the electromagnetic spectrum, while planet transits have uniform depth at all wavelengths. This project is to determine the feasibility of making simultaneous photometric measurements in different color filters to identify potential EB false-positives. Using the 12-inch telescopes at the Preston Gott Observatory, we first observe an ideal transit of a confirmed exoplanet and then a known eclipsing binary star. After analyzing the data collected, we present our findings along with our model of the photometric light curves. Simultaneous observations of an exoplanet candidate, while eliminating false-positives in the process, will enable smaller observatories and collegiate institutions to contribute to ongoing efforts to vet potential exoplanet candidates generated by current and future planet surveys. |
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G01.00039: Enhanced Visible Light Activity in Titania Nanotube Based Heterojunction Photocatalysts for Solar Fuel Generation Ram Neupane, Maggie Paulose, Oomman K Varghese The world energy consumption has been steadily increasing with technological advancements and the growing population. Bulk of this energy is currently derived from fossil fuels, which are known to be responsible for the greenhouse gas emission and associated environmental problems. Solar fuels such as hydrogen derived from water using semiconductor photocatalysts is a sustainable approach. Nonetheless, most photocatalysts hold drawbacks such as wide band gap and high recombination rate of photo-generated electrons and holes, limiting the practical applications. In a recent study, it was demonstrated that a visible light active photoelectrode for photoelectrochemical water splitting could be developed by coupling the wide bandgap titanium dioxide nanotubes with two dimensional (2D) narrow bandgap iron oxide called hematene (Nat. Nanotech., 13, 602-609, 2018). We have extended the studies to a 1D titania/2D FeTiO3 heterostructure and observed photo-generated carrier transfer from 2D FeTiO3 to 1D TiO2 through the heterojunction even though the positions of the conduction bands were not favorable for such a transfer. In this presentation, we discuss these results and the enhanced visible light driven solar photoelectrochemical hydrogen generation using these photoelectrodes. |
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G01.00040: Bio-mechanical Modeling and Analysis of Knee Joints Affected by Kyphosis Using Computational and Physical Calculations Minseo Lee, Amanda Kyung The physical and computational analysis can be used in cases where determining the clinical condition of patients is not easy. Kyphosis is one of the most well known disorders that elders suffer from the deformed thoracic vertebra causing incorrect postures and changing the center of mass of the body forward. In this paper, the effect of aging kyphosis on the patient 's use of stairs was experimentally investigated, and the most comfortable physical factors for kyphosis patients were suggested. Also, the effect of kyphosis on kinematics of knee joints and legs has been computationally performed. Using the free body of diagram of forces acting on the knee during loading and walking, bio-mechanical model depicting knee joint kinematics has been studied. Moment equilibrium and force equilibrium are also considered. Based on the fact that magnitude of the joint reaction force on knee joints can reach several times the body weight, the stability analysis of the knee and lower leg bone has been studied. This research includes two procedures: Study of mathematical modeling of the lower leg using bio-mechanics, and the development of mechanical analysis of the tibial bone. |
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G01.00041: Physical and Biochemical Study of the Antioxidants Used in Dental Bacteria Inhibitors Won Jun Lee, Sun Lee Cocoa beans contain various beneficial compounds including polyphenols and flavonoids, both of which positively impact dental health. Polyphenols benefit oral health primarily by preventing bacterial growth. The chemical structure of polyphenols allow the molecules to remove ROS(Reactive Oxygen Species), inhibit enzymes, and induce antioxidant activity. Periodontal disease is just one oral ailment that research has proven for polyphenols to be effective at preventing. Flavonoids such as catechin, epicatechin, and procyanidins are antioxidant-containing phytonutrients. In this paper, those antioxidants are studied to observe how they beneficially aid tooth health by delaying tooth decay.
This paper also illustrates how the tricyclic structure of flavonoids are able to thermodynamically give rise to such beneficial properties. In this project, we assessed the thermodynamical and stereochemical safety of several types of biochemical molecules that can be used as a biological and dental antioxidant.
Optimization configuration energies were collected in order to compare each chemical compound's safety and stability. Also, electro-potential maps were obtained in order to figure out each chemical compound's activities. |
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G01.00042: Study on the Physical and Biochemical Properties of Fullerene Derivatives and CNTs (Carbon Nano Tubes) for Cancer Treatment Jaesang Noh, Elise Kang Nanotechnology is ever more frequently the star of biochemistry as it continually unlocks methods to cure disease. Among its clinical applications, fullerenes and CNTs (Carbon Nano Tubes), as well as metal oxides, are being utilized in therapy for cancer patients. These nano-scaled compounds exhibit anti-tumor properties that inhibit cancer from spreading throughout the body, and a wide variety of fullerenes and CNTs have the potential to be applied in the therapeutic process. Once a fullerene is absorbed by one's cells, its C60 derivatives react to light radiation by transforming molecular oxygen into reactive oxygen, thereby triggering apoptosis in the HeLa cells and other cancer cells that are able to absorb such molecules. |
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G01.00043: Thermoelectric Modeling and Effective Analysis of the Peltier Module Using Numerical and Computational Method Sawoong Min, Richard Kyung Thermoelectric cooling uses the Peltier effect to generate a heat flux caused by temperature difference between two ceramic substrates which provide the platform for pellets. In this paper, variables such as semiconductor dimensions, material properties and initial temperatures are used as input data to find heat flux, temperature distributions, and electric properties in the thermoelectric cooling system. Computer simulations and numerical analysis are employed to find out the effect of the various factors on the electric field distribution in the Peltier system. Also, a calculator program which calculates the efficiency of the thermoelectric Peltier module that can be used in cooling systems. As a result, electric and thermodynamic properties such as the energy flux density and temperature distribution along the semiconductor pellets as functions of time are found. The objective of this study is to understand the mechanism of the thermoelectric coolers and to formulate equations of the electric and heat flux through P-type and N-type semiconductor pellets in the thermoelectric modules. Heat transfer by conduction is applied to the partitioned and non-partitioned modules by introducing mathematical and thermodynamic modeling. |
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G01.00044: Study on the Spectral and Acoustical Features of the Clarinet Sound Using Physical and Computational Analysis Joshua Rhee, Richard Kyung Acoustically, the clarinet sound is not closely related to the sound generated by other woodwind instrument. In this paper, acoustics knowledge was used to carry out physical and spectral analysis. The wave forms and spectrums of the clarinet and a few other instruments were calculated to compare their sound properties. The research implemented the sound of a clarinet instrument using harmonic equations and computer programs such as Mixcraft and MATLAB. The sound properties that were investigated were wavelength, fundamental frequency, harmonics, and trigonometric functions used in a Fourier transformation. It was noticed that several instruments had much more energy in the second, and/or third harmonics than in the first frequency. Also, a certain instrument showed the purest tones until a certain frequency. After crossing the frequency threshold, the tone became fuzzy. In the spectra analysis, we determined how the harmonics and power or energy of the clarinet were changed over time, but the pitch did not change. The main objective of this research was to study a musical note of the clarinet sound using digital audio workstation (DAW) and computational simulations. |
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G01.00045: Study on the Abnormalities in the Genetic Sequence in DNA Causing Leber Congenital Amaurosis (LCA) Namju Kim, Richard Kyung RPE65 is a gene critical for the visual function. Its mutation disrupts the vertebrate visual cycle, resulting in eye disorders such as RP and LCA. The role of RPE65 in the visual cycle is to catalyze the transformation of all-trans-retinyl ester to 11-cis-retinol and to allow the eye to detect light. [1] In LCA, a defective RPE65 gene results in a decreased regeneration of 11-cis-retinal. This breaks the phototransduction pathway and photoreceptors are unable to respond to light. Although malfunction of RPE65 causes LCA and RP eye disorders, research has shown that partial inhibition of RPE65 may treat age-related macular degeneration (AMD). This paper identifies and analyzes abnormalities in the genetic sequence that lead to mutations in patients with genetic eye disorders. In this paper, computational analysis of Arg91Trp mutation was performed to determine its resulting pathogenesis. First, sequence abnormalities in the gene of RP and LCA patients were identified. Then, sterochemical analysis was performed via gene editing program and molecular geometry analysis to observe the effect of the mutation on the peptide’s thermodynamic stability. |
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G01.00046: Study on Bio-images to Enhance Resolutions Using Computational and Numerical Simulations Eunsuh Kim, Lauren Chung In this paper, an alternative algorithm for bio-image processing was mathematically and computationally studied. Generally, digital bio-image subtraction and numerical filtering process such as LPF(Low Pass Filter) and HPF(High Pass Filter) are used to enhance the quality of normal biological and anatomic details of image. The main purpose of this research was to develop a better algorithm that would enhance the quality of the final radiograph images of human organs and structures. An ideal low pass filter would be able to increase the resolution of image as well as decrease the Ringing Artifact. In this paper, through comparison with conventional techniques, a few trigonometric functions and specific algebraic functions were tested to reduce Artifact. Compared to those produced by using a unit step function, the presented scheme improved the resolution of the resulting bio-image. Different variables were applied on the full K-space in order to find a most efficient filter, which can be used to produce better bio-image. Depending on the width of the LPF functions, the resolution of the resulting image using the non-Gaussian behavior differed. When the domain over the frequency domain was narrow, it produced blurry images. |
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G01.00047: Biochemical Stability and Safety Analysis of Nano-scaled Biochemical Compounds Used in Contrast Agents in MRI and Positron Emission Tomography(PET) Michelle Kung, Richard Kyung This project aims to determine the thermodynamic stability and safety of various nano-scaled biochemical compounds used in contrast agents in MRI and Positron Emission Tomography(PET) scanning. By using molecular editing computer programs and a computational chemistry method, this paper discovers the optimal form of the biochemical molecules used in bio-imaging and molecular diagnostics of Alzheimer's disease. Nanoparticles(NPs) are widely used for the purposes of fluorescent imaging, mainly of cells and tissues. For selective targeting of specific cells, surface functionalization has been developed using biochemical nanoparticles used in treatment of Alzheimer's and cancer disease. The Density Functional Theory (DFT), a computational chemistry modeling method, was used to model the electron properties of the compounds. Avogadro is an open-source molecular editing program with an auto-optimization feature which can determine the theoretical values of a structure's atomic properties. It allows users to build virtually any molecule with the optimized geometry according to various force field options.
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G01.00048: The Use of Assistive Technology in Science and Computer Model to Support People with Receptive Language Disorders Yeon Soo Kang, Elise Kang, Sunmee Lee Communication allows people to exchange information and meaning. It is ubiquitously essential skill for people to interact with each other. “Complex communication needs” is a term that describes people who have little or no speech ability. These communication impairments may be caused by physical, sensory, cognitive, or environmental factors. Speech and cognitive impairments prevent people with complex communication needs from communicating in conventional ways. In addition to speech impairments, individuals may have multiple disabilities, including physical, vision, hearing, sensory, or cognitive impairments.The goal of this research is to understand and propose solutions for issues that people with receptive language problems commonly experience. This research presents how the assistive technology and understanding languages with physical and computational method can help people with receptive language problems overcome the language barrier. This includes computer model that a software converts long, complex sentences to simple, easy-to-understand sentences and websites that offer information in the form of pictures, videos, and diagrams rather than text. |
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